Fracture Mechanics Methodologies for Structural Integrity Assessments and Fatigue Life Predictions under Multi-axial Non-proportional Loading

核压力容器、天然气管道、海洋和航空工业等高性能结构部件的安全运行具有重要的实际意义。任何这些部件的故障都是主要问题，因为它们可能导致对公众的伤害，对环境的破坏和高昂的维修成本。结构完整性评估和疲劳寿命预测旨在量化构件缺陷的影响，是保证高性能结构安全使用的关键。目前基于断裂力学的程序使用小尺寸样品的实验室测试结果来关联和预测全尺寸结构部件的响应。近年来，基于约束的断裂力学取得了重大进展，以确保从实验室测试中获得的性能可可靠地转移到全尺寸部件。在这些发展中，裂纹尖端三轴应力状态（所谓的“约束”）之间的差异，在试件和全尺寸部件进行了量化。

Safe operations of high-performance structural components such as those in nuclear pressure vessel, gas pipeline, offshore and aircraft industries are of significant practical interest. Failures of any of those components are major concerns since they can result in injury to the public, damage to the environment and high repair costs. Structural integrity assessments and fatigue life predictions aimed at quantifying the impact of defects in those components play a key role in ensuring the safe service of those high-performance structures. Current fracture-mechanics based procedures use results of laboratory tests on small-scale specimens to correlate and predict the response of full scale structural components. Significant developments in constraint-based fracture mechanics have taken place in recent years to ensure reliable transferability of properties obtained from laboratory tests to the full scale components. In those developments, the differences between the crack tip triaxial stress states (so-called “constraint”) in test specimens and full scale components was quantified.